This invention relates to method and apparatus for cutting multiple threads in a single, controlled step on a work product being sewn by a multi-needle sewing machine.
The use of multi-needle sewing machines for simultaneously forming a plurality of rows of stitches in a work piece materially reduces the amount of time involved in completing various work products. Such multi-needle operation does create problems, however. For example, when the work piece having several rows of stitches is completed, the operator is required to delay commencing a new sewing operation while the multiple threads extending from both the needles and the loopers of the machines are cut, usually by hand. It is also difficult for the operator to cut the threads expeditiously by hand, since it is generally necessary to pull the work product out of the machine and to cut the threads with scissors. Such manual operation wastes time and thread, since the operator usually must pull the work product too far out of the machine in order to see and reach the threads, resulting in either the lengths of thread at the needles and loopers being too long, or the threads of thread hanging from the finished work product being too long.
Heretofore, various types of automated thread cutters for mechanically cutting the threads extending from the needles and loopers have been developed. Prior art multiple thread cutters often require individual cutting members for each thread, as shown in U.S. Pat. No. 3,139,849 of Cohen et al, which are integral with the sewing machine itself, thus requiring machines especially built for specific applications. Still others, as exemplified in U.S. Pat. No. 3,532,065 of Marforio, act to pull the threads to be cut out of the sewing area, thus creating, at least in some cases, unnecessarily long lengths of thread.
Many prior art arrangements are limited with respect to the number of threads that can be cut; some require that the needles be staggered so that separate cutting elements can be applied to individual threads, and, as in the case of the Cohen et al arrangement, many are not adapted for use on a variety of machine configurations. Another characteristic of many prior art devices is the use of two cutters, one for cutting the needle threads, the other for cutting the looper threads, which at least in some arrangements, can only be done at the end of the work piece, and not at some intermediate point.